Abstract: A sizing sleeve for controlling the diameter of plastic tube includes pressurized sizing sleeve portions in which fluid is injected under pressure about the tube circumference to form a lubricating layer. Drainage zones axially separate and isolate adjacent pressurized portions to allow independent temperature and pressure control. Each pressurized portion has flow stabilizer reducing variations in flow responsive to changes in the lubricating layer pressure. The flow stabilizer may comprise a high pressure fluid source and high pressure drop constrictor comprising fine apertures, which may be formed as grooves milled into end surface of abutting sizing sleeve segments.

Abstract: A branched pipe fitting, such as a pipe tee, of plastics material has structure for preferential stiffening the side regions of the fitting. In one embodiment, the stiffening structure may include ribs crossing at the side apex point of the tee but not extending across the crutch points.